Until this summer, northwestern Colorado was perhaps best known for Dinosaur National Monument and a lonesome stretch of U.S. Highway 40.

But in that quadrant of this state lies about 60 percent of the nation's recoverable oil shale, and though the details are still sketchy, oil shale figures to play a major role in President Carter's ambitious plan to ease the country's energy pains.

Environmentalists, business and state and local officials agree that, whatever the specifics of Carter's plan, rapid development of oil shale will begin here soon, and only the pace and side effects remain undecided.

"It's got to take place. People are going to insist on it. I wish it didn't have to happen here," said former governor John Vanderhoof, president of Club 20, an economic development group representing interests in the resource-rich Western Slope of the state.

"Colorado will never be the same again. You're talking about an industry that's never been planned for," Mohamed el-Ashry, staff scientist in the Denver office of the Environmental Defense Fund, said of the expected shale boom.

Extraction of oil imbedded in shale rock is something northwestern Colorado long has expected, indeed looked forward to as an economic windfall.

But the president's proposals will accelerate the process, and towns with homespun names like Craig, Rifle and Meeker -- populations 3,000 to 5,000 -- will become small cities practically overnight.

Under Carter's plan, still subject to White House and congressional alteration, at least 400,000 barrels of oil from shale would be produced daily by 1990. The figures is based on projections that each plant constructed could squeeze out 50,000 barrels a day. It is estimated that 600 billion barrels of recoverable oil are encased in shale in the United States.

Much as the scarcity of western water needed for these plants and the specter of environmental ravaging have people nervous here, it is the vision of a radically, irrevocably changed life style that has stirred up the most anxiety in the wake of the president's speeches.

Bob Demos, head of the Colorado West Area Council of Governments based in Rifle, said that before the president's proposals aimed at ending American energy dependence were stated, it was projected that Rifle would quintuple in population by 1984. That prediction was based on 160,000 barrels a day from the oil shale industry.

"What we thought were really astronomical projections may actually double," Demos said of the energy proposals.

"These communities aren't ready to accept this growth in a healthy fashion . . . I think the whole community fabric as we know it is going to break down, or has the potential to break down," he added.

Problems associated with rapid oil shale development include unprecedented demands on housing, water and sewer systems, recreation areas, health facilities and roadways.

Others fear the new, multibillion-dollar industry will drag crime, prostitution, drug traffic, unemployment, high divorce rates and psychological problems into the barren area along with the obvious economic benefits.

Demos said crime in Rifle in the first quarter of 1978, shortly after ground on the first shale tracts was broken, was up 230 percent from the previous three months. And horror stories about widespread prostitution and corruption in the coal boomtown of Rock Springs, Wyo., have added to the uneasiness.

(Although there is a sizable amount of coal in Colorado, states such as Wyoming and Montana have as much and more, and Colorado won't be a focal point of the push to get synthetic fuel from liquefied coal.)

The fight over storage of precious western water, which has been subdued lately, is likely to be revived.

At a western governors' meeting in Denver last month, area leaders reminded a Carter aide that water is the lifeblood of the West. The president is being pressed to restore funds for water projects he killed.

Richard Lieber, executive vice president of the Rio Blanco Oil Shale Project, a venture which has committed $210 million to its tract near Rifle, said it is his "understanding" that 200,000 acre-feet of water can be made available to the shale industry each year.

Another Rio Blanco official estimated that one 50,000-barrel-a-day plant would need between 2,000 and 10,000 acre-feet of water each year to operate, depending on the technology used.

"Water is not a problem for us," Lieber said.

Because of water's crucial role in the extraction of oil from shale rock, Colorado agriculture commissioner Morgan Smith predicted some area farmers and ranchers "may come out in fairly good financial shape" through sales of water rights to the industry.

But Smith also said farmers and ranchers will have trouble keeping their labor with high-paying industry jobs so close by, and he expects some longtime farming operations to be forced to close.

On another front are environmental battles yet to be waged.

Rep. James Johnson (R-Colo.), whose district spans the state between Utah and Nebraska, said those who oppose the shale development will be "rolled over" because of the sense of urgency the energy crisis has assumed.

"I am concerned that with all this panic reaction, people might say 'the hell with the environment,'" Johnson said.

Despite pleas for maintaining high air, water and public health standards throughout the synthetic fuel push, industry appears insistent that environmental regulations be relaxed lest they drive up the cost of production.

"There has to be some environmental degradation permitted in order to go through with oil shale development," said Ken Monroe, executive director of the Colorado branch of the Rocky Mountain Oil and Gas Association.

Clifton Merritt, head of the Denver-based American Wilderness Alliance, was chagrined that so much more money is likely to be spent for synfuels than for solar and other cleaner, renewable sources of energy. He anticipates a strong, united lobbying effort by conservation groups such as his to minimize the environmental damage from the new industry.

"We don't want Colorado to become a national sacrifice area," Merritt said.

Undeniably, the economies of northwestern Colorado, the state and the region will benefit from the construction of the $1.5 billion shale plants.

Local government officials in some of the towns to be most affected admit that barely adequate services will now be brought up to snuff, and are concerned mainly that money to deal with problems of growth flows in at the same pace as the oil flows out.

Anxious westerners also wonder how much authority over state and local jurisdictions the president has given himself, and are eager to insure that the development process is, in the words of Utah Gov. Scott Matheson, "a partnership."

Still, for westerners who have long felt ignored by Washington in a variety of policy matters, an element of prestige travels hand in hand with all the possible adversity of the new synthetic fuel industry.

As former governor Vanderhoff said, this area "becomes the center of attention for the rest of the country. If the country survives, it's because we're able to produce here."